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Posted · How others solve it

 

 

Just because it's published somewhere does not mean it's accepted as prior art. ...

 

AFAIK the safest way to establish prior art is send the application in to the patent office, then later not pay the fees (let it expire), as you explained in a prior post. You don't gain protection, but nobody can patent your idea either at the novelty is not given any more. You could have done this with your ideas, even if you think patents and UMs open source strategy don't mix. Otherwise you live on the remains all other players leave in the field.

Wikipedia article on prior art - little chances for internet sources.

 

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Posted · How others solve it

There are two main problems with dualextrusion:

 

  • The two extruders have the same hight to build platform
  • Onzing second extruder

 

Adopting some ideas in this thread I thought about an dualextruderseesaw. Here's a little example how it could look like.

Dualextruderwippe Front

Dualextruderwippe 3D

 

Advantages of the dualextruderseesaw:

 

  • The unused extruder is rotated upwards, so he couldn't crash into workpiece.
  • When the unused extruder is onzing, the material drips on a small platform. The Platform could be extened with a brush at the end, so when the unused extruder is rotated in active position it is cleand.

 

Whats your opinion of this idea?

 

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Posted · How others solve it

Nice idea. The most challenging part might be to achieve a high precision in positioning.

 

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Posted · How others solve it

It could work but the challenge would be having a bearing with no "slop" so that changing nozzles results in the other nozzle being positioned exactly. Remember that some printers are producing layers that are 0.06 mm so you would need repeatability of much less than that probably on the order of 0.02mm or less to get satisfactory results. Note that this is along all three axes, X, Y and Z.

Instead of having small platforms to prevent ooze, they could be some type of metal that actually stops the oozing. Otherwise, the unused nozzle will lose some material requiring that it be primed with additional material just after switching to it. Although, my suggestion could cause clogging.

 

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Posted · How others solve it

I had a variation on that idea a while ago. Instead of just two on the same plane, rocking back and forth, put three or more around the bottom of a spherical shape, like electric type writers did with the letters on a big metal ball. Then you could swap out with 3 or 4 heads.

 

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Posted · How others solve it

The tilting print head idea has been around for a while, also in a Stratasys patent (see earlier post). As UM class machines suffer from the lack of high precision machining (in order to keep cost low), it makes sense to use elements with high precision/cost ratio. A ball bearing probably is the best performing construction element here, much better than self-made linear bearings. However, your sketch shows how to maximize nozzle inaccuracy for a given bearing play - the nozzles are too far away from the bearing contact points. Move the nozzle ends as close to the X bearings as possible to minimize the effect. This probably also means moving the tilt axis above the X rail.

The question is if a tilting head is really necessary (the Dimension Elite works with fixed nozzles, larger layer thickness though). If nozzle collisions are caused by too much play on the print head, one might question if adding even more potential accuracy issues is the way to go.

And of course you add the complication of a tilt motor. Not too difficult as there are two fixed stops, but still. It could be stationary as you'd want to go to a dump station when changing material anyway (BTW is this waste bin patented? The "purge tower" idea is IIRC). And of course you need the two extruder motors, making the print head heavy... And before you invent a single motor dual extruder head, look at the Stratasys patent describing this idea.

 

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Posted · How others solve it

I found a video with a dualextruder like my sketch:

I thought it is a relativly simple solution with low mechanical affords. My first sketch based nearly on the length of the UM2 extruder. The accuracy will be better if the distance between bearrings and extruder is shortend. I want to get the dualextruder built in the UM2 and there isn't much space!

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Posted · How others solve it

Here is another concept:

I think this one will have some accuracy problems, but it is nice for a brainstorming to find the best solution.

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